Sometimes, organisms need to be able to create energy when oxygen is not present. Alcoholic and lactic acid fermentation are two different metabolic pathways that can create energy without oxygen.
Fermentation is an anaerobic pathway that allows energy in the form of ATP to be created from glucose in the absence of oxygen.
Glycolysis occurs prior to fermentation. In this process, glucose is broken down to pyruvic acid. In addition, NADH and ATP are created.
In alcoholic fermentation, pyruvic acid is converted to ethanol. Carbon dioxide is released, and NADH is recycled into NAD+.
Lactic Acid Fermentation
In lactic acid fermentation, pyruvic acid is converted to lactic acid. NADH is recycled into NAD+.
Fermentation is important because it allows ATP to be made even when oxygen is not available. However, this process is less efficient than creating ATP when oxygen is present.